When I check about it in Websmater Tools, it shows 0 pages indexed. I'm not getting why is this problem happening. Googlebot fetches and submits it to be indexed but none of website's pages are indexed.

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Google is indexing your site, even if webmaster tools isn't reporting it yet. Webmaster tools can take weeks to update sometimes. Search for phrases from your pages in quotes to ensure that that page is actually indexed. Example
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Stephen Ostermiller♦Jul 21 '13 at 11:52